ICHTHYOLOGY. 



213 



Malacop. 



terygii 



Abdomi- 



nales. 



Saltno- 



nidse. 



Genus Hydrocyon, Cuvier. Extremity of the muzzle 

 formed by the inter-maxillary bones ; tlie maxillaries com- 

 mencing near or before the eyes, and completing the up- 

 per jaw. The tongue and vomer always smooth, but there 

 are conical teeth on both jaws. A large sub-orbitary bone, 



* thin and bare as tlie opercle, covers the cheek. 



Certain s|)ecies have a close row of small teeth on the 

 maxillary and palatine bones, the first dorsal fin corre- 

 sponding to the space between the ventral and anal fins. 

 They are of agreeable taste, and inhabit the rivers of the 



• torrid zone. To this group belongs the Hyd. falcalus, 

 Quoy and Gaim. Above of a violet tint, beneath pale, 

 but tinted generally with a shade of silvery. A silvery 

 band extends the whole length of the body from the oper- 

 cle to the tail, and at each extremity is marked with a dark 

 spot. The fins gray at the base, and brown at the extre- 

 mity. The eyes of a golden red. The scales small and 

 deciduous. The specimens brought by Freycinet were 

 from five to six inches in length. They were taken in 

 Brazil. 



Other species have a double row of teeth on the inter- 

 maxillaries and lower jaw, a simple row on the maxillaries, 

 and none on the palatine bones. The first dorsal fin is 

 placed above the ventrals. A Brazilian species, H. bre- 

 videns, Cuv., exemplifies this minor group. 



Others again have only a simple row of teeth on the 

 maxillaries and lower jaw, but the teeth are alternately 

 small and very large, especially the two second from be- 

 low, which pass through hollows of the upper jaw when 

 the mouth is shut. The lateral line is composed of scales 

 of a larger size, and the dorsal fin is so placed as to corre- 

 spond to the interval between the ventral and anal fins. 

 H. scomberoides, Cuv. or Cynodon vulpanus, Spix, is an 

 example of this peculiar form. 



Another form has the muzzle pointed, the maxillary 

 bones very sharp, and the inter-maxillaries and lower jaw 

 furnished with a single row of very close, small teeth ; the 

 body covered with strong scales. A Brazilian species, H. 

 lucius, Cuv. affords a characteristic example. 



A fifth form has teeth only on the inter-maxillaries 

 and lower jaw, and these few in number, but strong and 

 pointed. The first dorsal fin is placed above the ventrals. 

 A single species from the Nile, the Characinus dentex of 

 Geof. (Pois. d'Egypte), presents the sole example of this 

 limited group. 



Genus Citharinus, Cuvier. Characterised by their 

 depressed mouth, the upper edge formed entirely by the 

 inter-maxillary bones. The maxillaries small and without 

 teeth ; the tongue and palate smooth ; the adipose fin co- 

 vered H-ith scales, together with the greater part of the 

 tail. The species inhabit the waters of Africa. 



Some have the upper jaw only fiirnished with very fine 

 teeth ; the body elevated as in Serrasalmus, but without 

 the carinated or serrated abdomen. 



Salmo cyprinoides exemplifies this division of the genus. 

 Others have on both jaws a number of teeth, thickly placed 

 in several rows. These fish are more lengthened in their 

 form, and appear to lead to the next genus. Salmo ^Sgyp- 

 ticus, Linn, serves as an illustration. 



Genus Saurus, Cuvier.' Distinguished by its length- 

 ened and cylindrical form, and by the large scales, which 

 cover also the cheeks and opercles. The edges of the 

 upper jaws are formed entirely by the inter-maxillaries ; 

 and on each, as well as on the palatine bones and the 

 tongue, are numerous pointed teeth, which are wanting 

 on the vomer. The first dorsal fin is placed much pos- 

 terior to the ventrals, which are large. The interior struc- 



ture resembles that of the trouts. They are very vora- Malacop. 

 cious. tervifii 



This form is illustrated by the Salmo saurus of Bloch AluU 

 and Linn., a native of the Mediterranean ; above of a 

 greenish blue, varied with numerous narrow undulated 

 transverse bands, reaching as far as the lateral line, which 

 is itself bounded beneath by a continued stripe of brown ; 

 abdomen silvery. The fins pale, the pectorals crossed 

 with a few brown bars." 



S. variegattis, Lacepede, Quoy, and Gaimard. The 

 jaws, tongue, and palate with formidable sharp teeth. The 

 upper parts of a dull gray, banded transversely with eight 

 or nine brown bands, broad and irregular when ceasing at 

 the centre of the fish. The under parts tinted with rose 

 colour. The eye red and brilliant. In this fish the second 

 dorsal fin is so small as not easily to be perceived. Found 

 in the neighbourhood of the Sandwich Isles.^ 



«S'. gracilis, Quoy and Gaimard. A small species, reach- 

 ing only about four inches and a half in length. The co- 

 lours are unobtrusive, being a dull gray blotched with ir- 

 regular blackish spots, most defined on the sides and to- 

 wards the tail. All the fins are covered with brownish 

 specks, which on the pectorals are so disposed as to 

 form three transverse bands. This fish was also found in 

 the neighbourhood of the Sandwich Isles.* 



Genus Scopeles, Cuvier. Mouth and opening of the 

 gills wide; thejaws furnished with very fine teeth ; the up- 

 per jaw formed entirely by the inter-maxillaries; the tongue 

 and palate smooth ; the branchial rays from nine to ten ; 

 the adipose fin small, but having a trace of bony rays. The 

 species are small in size, and live in shoals. They are 

 found in the Mediterranean Sea. The Sc. Humboldtii of 

 Risso offers a characteristic example. 



Genus Aulopus, Cuvier. In this form the characters 

 of the Cod or Gadi, and Salmoiies, are united. The mouth 

 is widely cleft, the inter-maxillary bones, which form the 

 border of the upper jaw, are furnished, together with the 

 palatine bones, the vomer, and the lower jaw, with a nar- 

 row stripe of teeth en carde. The maxillary bones are 

 longer, and without teeth. The ventral fins are placed 

 almost under the pectoral fins, and have the outer rays 

 strong, and simply forked. The body, cheeks, and oper- 

 cles, are covered with large ciliated scales. Salmo Jilamen- 

 tosus of Bloch illustrates Aulopus. 



Genus Sternoptyx, Herman. These curious fish have 

 by Cuvier been placed under the above title at the conclu- 

 sion of his Salmonidae. They embrace two forms, which, 

 he thinks, will eventually be converted into sub-genera. 

 They are of small size, the body high, and very compress- 

 ed ; the mouth directed upwards. The humeral bones 

 form on the fore-part a sharp crest or ridge, terminated be- 

 low by a small spine. The pelvic bones form another and 

 similar crest, also terminated by a small spine placed before 

 the ventral fins, which are so minute as to have escaped 

 the observation of the first observer. On each side of the 

 last ridge there is a row of small hollows, h hich has been 

 regarded as a fold of the sternum, and has suggested the 

 name oi' Sternoptyx. Before the dorsal fin there is a bag or 

 membranous ridge, and behind this fin there is a small 

 membranous projection, which is thought to represent the 

 adipose fin of the true Salmones. 



The first form of this genus has very fine teeth, with five 

 rays to the branchial membrane, and is represented by St. 

 Hermannii. The second has the teeth hooked, and nine 

 rays to the branchial membrane. St. Olfersii exhibits the 

 only known example. Both species are from the warmer 

 parts of the Atlantic Ocean. 



' Named from their lengthened Saurian or lizard-like form, and distinguished from the other groups derived by Cuvier from tie 

 genus Characinus of Artedi, by the branchial rays ranging from eight to fitteen in number. 



• Shaw, General Zoology, vol. v. • Voyage dc Fref/cincl. * Ibid, 



